DNA or deoxyribonucleic acid is possibly the most important thing in any living organism. DNA is inside every cell of the body and contains information that your cells use to grow and repair. It is your DNA that makes you individual because it controls your hair colour, eye colour and all other characteristics. The information that is contained in DNA is passed between generations in the breeding process. What?DNA is made up of atoms of oxygen, hydrogen, carbon, nitrogen and phosphorus - nothing too special when you put it like that - which join together to form a large molecule of DNA. A molecule of DNA is made up of two chains that line up side by side and wind around each other to create a double helix. Within a chain of DNA there are four building blocks known as A, C, G and T or Adenine, Cytosine, Guanine and Thymine. A strand of DNA consists of a random sequence of these four building blocks and it is the order that they're attached which dictates the information that your DNA molecules contain. In each cell of DNA there are around three billion of these four building blocks joined together - a different sequence in everyone. Considering its complexity the structure of DNA is surprisingly simple as it looks like a twisted ladder, the sides are made up of sugar and phosphate molecules and the rungs are the four bases A, T, G and C and the DNA of all living things is made up in the same way. Where?In almost every cell there is a nucleus and this contains 46 chromosomes or 23 pairs which are also unique to you. It is inside each of these chromosomes that you'll find your DNA. Your cells contain 23 pairs of chromosomes because when you're conceived the 23 chromosomes that are in the egg link up to the 23 in the sperm - effectively it means that you get half of them from your mum and half from your dad. How?In order for DNA to be able to transfer information to every cell of the body the cells have to replicate from the moment the egg and sperm first meet. As soon as these two meet a complete set of DNA is formed and that one cell splits into two and then those two into four and this process continues throughout your life as you grow and dead cells need to be replaced. The majority of the time cells divide and replicate perfectly and the DNA is an exact match, however sometimes mutations in the DNA can occur in which case the new cell usually dies. However, there are occasions when these mutated cells can survive in which case serious problems can occur. Sometimes though, these mutations in the DNA can be beneficial to an organism and if this is the case then when the cell comes to replicate again this mutation will remain. It is these positive mutations that represent the beginning of evolution.

Helen Jacobs is a scientific expert and when she needs new supplies she buys them from Primer Design